Production of PU foams

Abstract

Process for producing PU foams by reacting at least one polyol component with at least one isocyanate component in the presence of one or more catalysts that catalyse the isocyanate-polyol and/or isocyanate-water reactions and/or isocyanate trimerization, and optionally one or more chemical or physical blowing agents, with use of SiOC-bonded polyether siloxanes having branching in the siloxane moiety, prepared from branched siloxanes bearing acetoxy groups, wherein a sufficient amount of the SiOC-bonded polyether siloxane having branching in the siloxane moiety is added that the proportion by mass of this polyether siloxane (e) based on the finished PU foam is from 0.0001% to 10% by weight.

The invention claimed is: 
     
       1. A process for producing a polyurethane foam (PU) foam by reacting
 (a) at least one polyol component with 
 (b) at least one isocyanate component 
 in the presence of 
 (c) one or more catalysts, which catalyse the isocyanate-polyol and/or isocyanate-water reactions and/or isocyanate trimerization, and 
 (d) optionally one or more chemical or physical blowing agents, 
 with use of 
 (e) SiOC-bonded polyether siloxanes having branching in the siloxane moiety, prepared from (f) branched end-equilibrated siloxanes bearing acetoxy groups, 
 wherein a sufficient amount of the SiOC-bonded polyether siloxane (e) having branching in the siloxane moiety is added that the proportion by mass of the SiOC-bonded polyether polyether siloxane (e) based on the finished PU foam is from 0.0001% to 10% by weight. 
 
     
     
       2. The process according to  claim 1 , wherein the PU foam is a rigid PU foam, a flexible PU foam, a viscoelastic PU foam, an HR PU foam, a hypersoft PU foam, a semirigid PU foam, a thermoformable PU foam or an integral PU foam. 
     
     
       3. The process according to  claim 1 , wherein the reaction is effected with use of
 g) water, and/or 
 h) one or more organic solvents, and/or 
 i) one or more stabilizers against oxidative degradation, and/or 
 j) one or more flame retardants, and/or 
 k) further foam stabilizers other than component (e), based on siloxanes and/or polydialkylsiloxane-polyoxyalkylene copolymers, 
 and/or 
 l) one or more further additives, selected from the group of the surfactants, biocides, dyes, pigments, fillers, antistatic additives, crosslinkers, chain extenders, cell openers and fragrances. 
 
     
     
       4. The process according to  claim 1 , wherein the branched end-equilibated siloxanes (f) bearing acetoxy groups are obtained from the reaction of
 iv) silanes and/or siloxanes bearing alkoxy groups, and/or 
 v) silanes and/or siloxanes bearing hydroxy groups, and/or 
 vi) simple siloxane cycles and/or DT cycles, 
 
       with acetic anhydride, superacid, trifluoromethanesulfonic acid, or acetic acid. 
     
     
       5. The process according to  claim 1 , wherein the branched end-equilibated siloxanes (f) bearing acetoxy groups are prepared using a silane and/or siloxane bearing alkoxy groups and containing at least one T and/or Q group, and/or DT cycles. 
     
     
       6. The process according to  claim 1 , wherein the SiOC-bonded polyether siloxanes (e) branched in the siloxane moiety are prepared by reacting the branched end-equilibated siloxanes (f) bearing acetoxy groups with polyetherols. 
     
     
       7. The process according to  claim 6 , wherein the reaction specified therein of the branched end-equilibated siloxanes (f) bearing acetoxy groups with polyetherols using an inert solvent is effected using a solvent that is inert and at the same time forms an azeotrope with acetic acid formed and possibly already present. 
     
     
       8. The process according to  claim 6 , wherein the reaction specified therein of the branched end-equilibated siloxanes (f) bearing acetoxy groups with polyetherols is effected in a solvent-free manner. 
     
     
       9. The process according to  claim 1 , wherein the branched end-equilibated siloxanes (f) bearing acetoxy groups are reacted with polyetherols in the presence of at least one base. 
     
     
       10. The process according to  claim 1 , wherein the SiOC-bonded polyether siloxane (e) having branching in the siloxane moiety contains polyether residues, having the following formula (III):
   —O—(CHR′CHR″O—) m —(CH 2 CH 2 O—) n —(CH(CH 3 )CH 2 O) o —R′″  (III)
 
 with 
 R′ is hydrogen, a saturated alkyl group having 1-18 carbon atoms or an aromatic radical, 
 R″ is hydrogen, a saturated alkyl group having 1-18 carbon atoms or an aromatic radical, 
 R′″ is identical or different, saturated or unsaturated alkyl radicals having 1-18 carbon atoms, 
 m=from 0 up to 250, 
 n=from 0 up to 250, 
 o=from 0 up to 250, 
 wherein the sum total of m, n and o is equal to or greater than 3. 
 
     
     
       11. The process according to  claim 1 , wherein the branched end-equilibated siloxanes (f) bearing acetoxy groups are reacted with polyetherols in the presence of sodium hydrogencarbonate, ammonia, or an organic amine. 
     
     
       12. The process according to  claim 10 , wherein
 R′ is a methyl or ethyl group or a phenyl radical, 
 R″ is a methyl or ethyl group or a phenyl radical, 
 R′″ is identical or different, saturated or unsaturated alkyl radicals having 1-4 carbon atoms, 
 m=from 0 up to 50, 
 n=from 5 up to 50, 
 o=from 5 up to 50.